Electrical conductors have previously been inked, or painted, on film substrates. Conductive ink or paint is readily available for painting, or printing of circuits and conductors on plastic films, which films are commonly known and commonly available for use as electrical substrates. The use of electrically-conductive paint in making electrical conductors is well-known to those skilled in the art. See, for example, U.S. Pat. No. 3,325,580, for Musical Instrument Utilizing Piezoelectric Transducer, issued June 13, 1967, to L. M. Barcus et al., Col. 6, line 11, et seq.
For information pertaining to conductive inks, conductive adhesive inks, adhesives and surface mount technology (SMT), in general, refer to Radio-Electronics, page 59 et seq., November, 1987, "Introduction to SMT", by Forrest M. Mims, III.
Most any form of graphical reproduction may be used in the process of the invention or manufacturing the device of the invention, to apply the conductive material (ink, paint, etc.) in the desired electrical pattern. Printed circuit board technology has long used photographic, photolithographic, etching and other techniques to create electrical conductors on fiberglass boards.
Conductive "ink" or "paint" are meant herein to be synonymous and each are intended herein to mean and include the other, as are "printing" and "painting", in this connection. Silk screening is also considered "inking" or "painting". So, too, "graphical reproduction" is intended to include "printing" and "painting" and all other methods of applying "ink" or "paint" to paper, plastic or other carrier. All such methods are included within the meaning of "graphical reproduction", whether it be by typography, photography, lithography, plotting, recording, offset printing, silk, plastic or stainless steel screening or otherwise. Any suitable methods of depositing or forming the conductive material in the desired Pattern may be used.
Touch-type switches, or film, or membrane, switches have been known for some time. One good example of touch switches in daily use are those in the switch panel of a microwave oven. Household washers and dryers commonly use such touch panel switches. The switches customarily provide a momentary electrical connection between two conductors which acts to complete an electrical path and trigger, electrically activate or deactivate, another electrical element. For example, a flip-flop circuit, relay or other bistable circuit may be caused to change state or to be "set" by such momentary trigger. The flip-flop then provides its output as input to some other electrical circuitry.
Electrical connectors come in many sizes, shapes and structures. It is difficult to connect a connector to a painted, evaporated or printed conductor by soldering, welding, wire wrap, fusion bonding or other standard means of electrical connection. The difficulty is compounded when there are multiple conductors and multiple layers of conductors. In making electrical connections, adhesive connectors are known to those skilled in the art. For example, the use of conductive epoxy in a conductive adhesive to connect electrical leads to a piezoelectric device is taught, for example, in U.S. Pat. No. 4,785,704, Musical Instrument Transducer, issued Nov. 22, 1988, to Lawrence R. Fishman. See Col. 2, line 41 et seq. In that patent, the conductors are soldered to the connectors. Also, in U.S. Pat. No. 3,325,580, Musical Instrument Using Piezoelectric Transducer, issued June 13, 1967, to L. M. Barcus et al, is taught coating a piezoelectric plate with a conductive paint to provide electrodes. See Col. 6, lines 15 et seq. See, also, the article by Forrest Mims, III, in Radio-Electronics, referred to above, for a discussion of adhesives and conductive adhesives.
The problem posed is how to connect thin, flat film conductors to connectors and switches, particularly those that are formed by depositing a thin film of conductive inks or paints on a thin film substrate. Soldering or welding connectors and conductors to "painted" films are usually difficult and often unsatisfactory.